1. Field
Apparatuses consistent with exemplary embodiments relate to a photographing apparatus, a motion estimating apparatus, an image compensating method, a motion estimating method, and a computer-readable recording medium, and more particularly, to a photographing apparatus which can check a uniformly accelerated motion thereof through continuously captured images, a motion estimating apparatus, an image compensating method, a motion estimating method, and a computer-readable recording medium.
2. Description of the Related Art
An imaging device refers to a part which generates an image in a mobile phone camera or a digital still camera (DSC). Examples of the imaging device include a charge-coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor.
The CCD image sensor refers to a device in which metal-oxide-silicon (MOS) capacitors are very close to one another, and charge carriers are stored in and transferred to the MOS capacitors. The CMOS image sensor refers to a device which adopts a switching method of forming and using MOS transistors by the number of pixels by using CMOS technology for using a control circuit and a signal processing circuit as peripheral circuits in order to sequentially detect outputs.
The CCD image sensor attracts the widest attention as a conventional image sensor and is currently widely used in a digital camera, a camera phone, or the like. However, as the importance of the camera phone stands out, it is important to reduce power consumption of the camera phone. Therefore, interest in the CMOS image sensor has increased. The CMOS image sensor is manufactured in a CMOS process for producing general silicon semiconductors, and thus, is small and cheap, and power consumption thereof is low.
A method of reading an optical image of a subject formed in an imaging area of an imaging device is classified as a global shutter method and a rolling shutter method. The global shutter method refers to a method by which all pixels of the imaging area read the optical image at a same time. The rolling shutter method refers to a method by which one or several pixels of the imaging area sequentially read the optical image.
The CMOS image sensor may apply both to the global shutter method and to the rolling shutter method. If the CMOS image sensor applies the global shutter method, all pixels read the optical image of the subject at a same time. Therefore, even if the subject moves, a captured image is not transformed.
If the CMOS image sensor applies the rolling shutter method, one or several pixels sequentially read the optical image. Therefore, if the subject is moving or a photographing apparatus is being moved, a captured image may be transformed. Accordingly, if a subject that is moving is captured, a photographing apparatus applying the rolling shutter method has difficulty capturing a normal image.
A technique for compensating for an image distortion of the rolling shutter method is classified into an optical image stabilizer (OIS) technique and a digital image stabilizer (DIS) technique.
The OIS technique refers to a method by which a motion of a photographing apparatus is measured by using a gyro-sensor, and an image sensor or a lens of the photographing apparatus is moved in an opposite direction in order to compensate for the motion of the photographing apparatus. The OIS technique is very effective, but is costly. Also, if the motion of the photographing apparatus exceeds a displacement range provided by the OIS technique, there is no compensation for the rolling shutter phenomenon.
The DIS technique refers to a method by which a motion between images is estimated by using a digital signal processing method, wherein a distortion of an image is compensated for according to the estimated motion.
However, the DIS technique has problems with a calculation amount and accuracy. In detail, a large amount of calculation is required to estimate a motion between images in a camcorder or a camera which is to process a moving picture in real time. Also, a motion of a photographing apparatus is estimated on the assumption that the photographing apparatus moves at a constant velocity. Therefore, an accuracy problem exists.